Biology Reference
In-Depth Information
1200
1000
800
600
400
200
0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
L3 (mm)
FIGURE 12.2
Intersite difference of size-weight index in
Nereis diversicolor
originating from Authie (⬥) and Seine (⬦) estuaries
(Durou 2006).
within the framework of a survey on the condition of populations from one species, energy
reserves could provide essential information on the individuals' ability to survive, grow,
and reproduce, and consequently they yield long-term information about the fitness of a
population. For example, in
Nereis diversicolor
, originating from both clean and contami-
nated sites, the measured energy reserve levels of organisms from the contaminated site
generally decrease and are associated with mass loss (see Section 12.2 and Figure 12.2).
And yet, these results are not universal since the effects vary depending on the studied
species and involved contaminants. In
Biomphalaria glabrata
, a freshwater gastropod mol-
lusk, exposure in the laboratory to 0.1 and 0.05 mg Cd L
-1
; 0.5, 0.1, and 0.05 mg Pb L
-1
; and
0.5, 0.1, and 0.05 mg As L
-1
, showed that arsenic has a stronger impact on the glycogen in
the gonad than cadmium (Ansaldo et al. 2006). The cadmium toxic effect is counterbalanced
by metallothionein, which explains the latter result (Amiard et al. 2006). In a field study,
the earthworm,
Dendrobaena octaedra
, was collected from polluted and unpolluted reference
areas. Pb, Cd, and Cu accumulation did not correlate with glycogen reserves of worms,
whereas Al, Ni, and Zn were negatively correlated with glycogen levels. These results sug-
gest that, in these earthworms, coping with different metals is associated with differential
energy demands depending on the detoxification strategy involved (Holmstrup et al. 2011).
12.1.3 Cellular Energy Allocation
If the adenylate charge or energy reserves provide evidence of the available energy in
organisms, it is also necessary to consider integration parameters of both the availability
and consumption of energy by organisms. In this regard, the CEA accounts for the net
energy budget at cellular level (De Coen and Janssen 1997):
t
t
∫
∫
Et
d
−
Et
d
a
c
CEA
=
0
0
.
(12.1)
t
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